Processing method and processing unit for substrate

ABSTRACT

A processing unit for a substrate comprises a partition  6  provided between an atmospheric area S 1  and an inert gas area S 2.  The partition  6  has an opening  22  to communicate the atmospheric area S 1  and the inert gas area S 2.  A door  23  is provided at the opening  22  to open and close it. Carrier holding means  11  is provided for holding a carrier  2  of the substrate in such a manner that the carrier  2  comes in contact with the opening  22  on the side of the atmospheric area. Inert gas replacing means  56  is provided for replacing a gas in the carrier  2  with an inert gas by introducing the inert gas into the carrier  2  when the door  23  closes the opening  22  and the carrier  2  comes in contact with the opening  22  on the side of the atmospheric area by the carrier holding means  11.  This processing unit can perform the process of the substrate without increasing the concentration of the oxygen in the inert gas area S 2  by preventing leakage of the air from the atmospheric area S 1  into the inert gas area S 2.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a processing method for a substrate anda processing unit for a substrate.

[0003] 2. Disclosure of the Prior Art

[0004] Processes for manufacturing semiconductor devices include stepsin which semiconductors as substrates undergo processes such asoxidation, diffusion, CVD (Chemical Vapor Deposition) or the like.Thermal processing units are often used for conducting the variousprocesses. A conventional thermal processing unit comprises: anoperation area where an operator or an automatic conveying robot holdsand conveys a carrier housing semiconductor wafers, and a loading areawhere semiconductor wafers in the carrier are transferred to awafer-boat as a holder of substrates which is then loaded into orunloaded from a thermal processing furnace.

[0005] In such thermal processing units, it is preferable for apartition (bulkhead) to be provided between the operation area which isexposed to the atmosphere and the loading area. The partition allows theloading area to remain cleaner than the operation area and prevents anatural oxidation film from forming on the semiconductor wafers. Theloading area should also be preferably filled with an inert gas such asnitrogen. A closed-type carrier, whose entrance for semiconductor waferscan be hermetically closed by a lid, should also be preferably used inthe thermal processing unit in order to prevent the semiconductor wafersfrom being contaminated with particles.

[0006] An opening is provided in the partition between the operationarea and the loading area. A door is provided at the opening to open andclose it. When processing the semiconductor wafers, the lid of thecarrier is aligned to be in contact with the opening, and the door andthe lid are opened to communicate the interior of the carrier with theloading area. The semiconductor wafers are then conveyed from theinterior of the carrier to the wafer-boat in the loading area via theopening. The wafer-boat is then loaded in the thermal processing furnaceto perform the prescribed processes on the semiconductor wafers. The wayof opening the door and the lid together is described in Japanese PatentLaid-Open No. 8-279546.

[0007] The interior of the carrier is full of the atmospheric air unlessit is filled with another gas such as an inert gas. Because of this, theair in the carrier may flow into the loading area when the carrier isaligned with the opening and the door and the lid are opened. Theconcentration of the oxygen in the loading area increases if the air inthe carrier flows into the loading area. This makes the replacement ofthe atmospheric air with an inert gas more time-consuming and increasesthe possibility of oxidation film forming on the semiconductor wafers.This may have a bad effect on processing.

SUMMARY OF THE INVENTION

[0008] Therefore, the object of this invention is to provide aprocessing unit and method for a substrate, which can perform theprocess of the substrate without increasing the concentration of theoxygen in the loading area by preventing the leakage of the air from theoperation area into the loading area.

[0009] To achieve the above objects, this invention is characterized bya feature wherein a processing unit for a substrate comprises: apartition provided between an atmospheric area and an inert gas area,and having an opening to communicate the atmospheric area with the inertgas area, an door provided above the opening to open and close it,carrier holding means for holding a carrier of the substrate in such amanner that the carrier comes in contact with-the opening on the side ofthe atmospheric area, and inert gas replacing means for replacing a gasin the carrier with an inert gas by introducing the inert gas into thecarrier when the door closes the opening and the carrier comes incontact with the opening on the side of the atmospheric area by thecarrier holding means.

[0010] In addition, to achieve the above objects, this invention ischaracterized by a feature wherein a processing method for a substrateby using a processing unit for the substrate comprising: a partitionprovided between an atmospheric area and an inert gas area, and havingan opening to communicate the atmospheric area with the inert gas area,an door provided above the opening to open and close it, carrier holdingmeans for holding a carrier of the substrate in such a manner that thecarrier comes in contact with the opening on the side of the atmosphericarea, and inert gas replacing means for replacing a gas in the carrierwith an inert gas by introducing the inert gas into the carrier when thedoor closes the opening and the carrier comes in contact with theopening on the side of the atmospheric area by the carrier holdingmeans, comprises; a step of closing the opening by the door, a step ofholding the carrier including the substrate by the carrier holding meansin such a manner that the carrier comes in contact with the opening onthe side of the atmospheric area, a step of replacing the gas in thecarrier with the inert gas by the inert gas replacing means, and a stepof opening the door to communicate the interior of the carrier replacedwith the inert gas with the inert gas area via the opening.

[0011] According to these features, the process of the substrate can beperformed without increasing the concentration of the oxygen in theloading area by preventing the leakage of the air from the operationarea into the loading area.

[0012] Preferably, the carrier may have an opening part to communicatewith the opening when the carrier comes in contact with the opening onthe side of the atmospheric area, and the inert gas replacing means mayhave an inert gas supplying hole and a gas exhausting hole which areopenly provided in the opening.

[0013] Preferably, the carrier may have a lid to open and close theopening part of the carrier.

[0014] Preferably, a lid opening-closing mechanism may be mounted on thedoor for holding the lid of the carrier and for opening and closing it.

[0015] Preferably, a door opening-closing mechanism may be mounted onthe partition for opening and closing the door, and the dooropening-closing mechanism may be adapted to open the door in a statewhere the lid opening-closing mechanism holds the lid of the carrier.

[0016] Preferably, the carrier holding means may have carrierpositioning means for positioning the carrier in such a manner that thecarrier comes in sealing contact with the opening on the side of theatmospheric area.

[0017] Preferably, the carrier and the opening in the partition may beadapted to come in sealing contact with each other via a sealingelement.

[0018] Preferably, the partition may have a second opening tocommunicate the atmospheric area with the inert gas area, and the unitfurther may comprise: a second door provided above the second opening toopen and close it, second carrier holding means for holding a carrier ofthe substrate in such a manner that the carrier comes in contact withthe second opening on the side of the atmospheric area, and second inertgas replacing means for replacing a gas in the carrier with an inert gasby introducing the inert gas into the carrier when the second doorcloses the second opening and the carrier comes in contact with thesecond opening on the side of the atmospheric area by the second carrierholding means.

[0019] Preferably, the door may be adapted to move downward to open theopening, and the second door is adapted to move upward to open thesecond opening.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a schematic vertical sectional view of an embodiment ofthe vertical thermal processing unit according to the invention;

[0021]FIGS. 2a and 2 b are explanatory views showing a way for openingand retracting a door closing an opening in a partition of the verticalthremal processing unit in FIG. 1;

[0022]FIG. 3 is a schematic plan view of the vertical thermralprocessing unit in FIG. 1;

[0023]FIG. 4 is a schematic perspective view of the door and a lidopening-closing mechanism of the vertical thermal processing unit inFIG. 1;

[0024]FIG. 5 is a schematic perspective view of the carrier and the keyoperating mechanism of the vertical thermal processing unit in FIG. 1;

[0025]FIG. 6 is a schematic perspective view of various mechanismsprovided adjacent to the carrier stage of the vertical thermalprocessing unit in FIG. 1;

[0026]FIGS. 7a to 7 c are explanatory views showing a way for openingand closing the lid and the door of the vertical thermal processing unitin FIG. 1;

[0027]FIG. 8 is a front view of an example of the inert gas replacingmeans;

[0028]FIG. 9 is an enlarged partial sectional view of an example of thesealing means of the rotating shaft passing through the door;

[0029]FIG. 10 is an explanatory view of another example of the fixingmeans for fixing the carrier to the opening in the partition; and

[0030]FIG. 11 is an explanatory view of another lid opening-closingmechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0031] Embodiments of the invention will now be described in more detailwith reference to FIGS. 1 to 11. FIG. 1 schematically shows a verticalsection of an embodiment of the vertical thermal processing unitaccording to the invention. FIGS. 2a and 2 b explain a way of openingand retracting a door closing an opening in a partition of the verticalthermal processing unit in FIG. 1. FIG. 3 is a schematic plan view ofthe vertical thermal processing unit in FIG. 1.

[0032] In these figures, a numeral sign 1 designates a housing formingoutside walls of the vertical thermal processing unit disposed in aclean room. The interior of the housing 1 is divided by a partition(bulkhead) 6 into an operation area S1 into and from which carriers 2are conveyed and in which the carries 5 are kept, and a loading area S2where semiconductor wafers W (substrates to be processed) in thecarriers 2 are transferred to wafer-boats 4 which are loaded into orunloaded from a vertical type thermal processing furnace 5.

[0033] An entrance 7 is provided in front of the housing 1 forintroducing and discharging the carriers 2 by an operator or anautomatic conveying robot. The entrance 7 is provided with a door 8which can move vertically to open and close the entrance 7. A stage 9 isprovided in the operation area S1 for placing the carrier 2 thereon.Shelf-like storing sections 10 are formed above the stage 9 and near theupper portion of the partition 6 for storing a plurality of the carriers2.

[0034] Two stages (carrier stages) 11 are provided in vertically spacedpositions on the side of the partition 6 as tables for placing thecarriers 2 thereon. A carrier transferring mechanism 12 is arranged inthe operation area S1 for transferring the carriers 2 to and from thestage 9, the storing sections 10 and the stages 11. The carriertransferring mechanism 12 comprises: an elevating arm 14 which can bemoved vertically by an elevating mechanism 13 provided on a side of theoperation area S1, and a transferring arm 15 mounted on the elevatingarm 14 for supporting the bottom of the carrier 2 to horizontallytransfer the carrier 2.

[0035] The thermal processing furnace 5 is disposed in a rear and upperportion in the loading area S2. The thermal processing furnace 5 has afurnace opening in the bottom thereof. A lid 16 is provided below thefurnace 5. The lid 16 is adapted to be vertically moved by an elevatingmechanism (not shown) for loading a wafer-boat 4 into and unloading itfrom the furnace 5 and for opening and closing the furnace opening. Thewafer-boat 4, which can hold a large number of semiconductor wafers W invertical equally spaced multistairs, is adapted to be placed on athermal pedestal 17 on the lid 16. The thermal processing furnace 5 hasa shutter (not shown) for closing the furnace opening after the lid 16is moved downward to unload the wafer-boat 4.

[0036] As shown in FIG. 3, two boat-placing portions 18 are disposedadjacently in a side region of the loading area S2 for placing thewafer-boat 4 thereon when transferring semiconductor wafers W into andfrom the wafer-boat 4. A moving mechanism 19 is arranged in the loadingarea S2 for transferring semiconductor wafers W between the wafer-boat 4on any one of the boat-placing portions 18 and the carrier 2. The movingmechanism 19 can be moved by an arm 20 from a waiting position shown insolid lines in FIG. 3 to an operating position shown in imaginary linesin the same figure. A boat-conveying mechanism 21 is arranged forconveying the wafer-boat 4 between the lid 16 and the boat-placingportions 18.

[0037] A clean atmospheric air, which is passed through filters (notshown), is supplied into the operation area S1, so that the operationarea S1 is filled with the clean atmospheric air. On the other hand, aninert gas such as nitrogen (N₂) is supplied into the loading area S2, sothat the loading area S2 is filled with the inert gas. As shown in FIG.4, the partition 6 separating the loading area S2 from the operationarea S1 has two, upper and lower openings 22, with each of which thecarrier 2 is adapted to come into contact on the side of the operationarea S1. As shown in FIG. 5, each opening 22 is provided with a lid 25for opening and closing the opening 22. The opening 22 is formed in sucha manner that the size of the opening 22 is the same as that of awafer-entrance 24 of the carrier 2, so that semiconductor wafers W canbe transferred into and from the carrier 2 through the opening 22 andthe wafer-entrance 24.

[0038] The structure of the carrier 2 and the opening and closingfunction of the lid 25 of the carrier 2 will be described in more detailbelow.

[0039] As shown in FIG. 5, the carrier 2 is a so-called closed type,which can house a number of, for example 13 or 25 semiconductor wafers Wand which can be hermetically closed by the lid 25. The carrier 2comprises a container for housing and holding semiconductor wafers W inmultistairs in horizontal attitude and in vertically spaced relation bya prescribed pitch. The diameter of the semiconductor wafer W is forexample 30 mm. The lid 25 is removably attached at the wafer-entrance 24formed in front of the carrier 2 in such a manner that the lid 25 cansealingly close the wafer-entrance 24. The carrier 2 and the lid 25 aremade of, for example, a synthetic resin. A flange 26 is formed along thesides of the wafer-entrance 24.

[0040] As shown in FIG. 5, the lid 25 of the carrier 2 has one or more,for example two, key holes 29. Lock-pins (not shown) are arranged tostick out of the upper edge and the lower edge of the lid 25 when eachkey 28 of a key handling mechanism 27 is inserted into each key hole 29and is rotated in a direction. Then the lock-pins can fit in recesses(not shown) formed at the upper edge and the lower edge of thewafer-entrance 24 of the carrier 2 and can lock the lid 25 in a closingposition. The lock-pins (not shown) are also adapted to be withdrawn tothe upper edge and the lower edge of the lid 25 when each key 28 of thekey handling mechanism 27 is inserted into each key hole 29 and isrotated in the opposite direction. Then, the lock-pins can leave therecesses formed at the upper edge and the lower edge of thewafer-entrance 24 of the carrier 2 and can release the lid 25 from theclosing position. Normally, the lid 25 is locked in the closingposition. The lid 25 is also adapted to be held by the keys 28 when thelid 25 is released from the closing position by inserting the keys 28into the key holes 29 and by rotating the keys 28.

[0041] As FIG. 5 shows, the key handling mechanism 27 comprises: ahandling member 31 which can be shifted in a lateral direction by rightand left air cylinders 30 as driving means, rotating members 32 each ofwhich has a rotating shaft 33 and can be rotated by the handling member31 around the shaft 33, and the keys 28 attached to the tips of therotating shafts 33 of the rotating members 32. The handling member 31and the rotating members 32 are so connected by links 34 that linearlateral movement of the handling member 31 can be converted into arotating movement of the rotating members 32. Alternatively, they may belinked by a gear mechanism. The lock-pins (not shown) are adapted to bewithdrawn to release the lid 25 from the closing position and the lid 25is held by the keys 28 when each key 28 is inserted into each key hole29 of the lid 25 and is rotated. As shown in FIG. 4, the key handlingmechanism 27 is mounted at a front-rear moving frame 49.

[0042] Then the structures of the openings 22 and doors 23 for theopenings 22 are described in more detail as follows.

[0043] As shown in FIG. 4, the partition 6 is formed to have a verticalgroove. A part of the groove forms a recess 35 for accommodating thefront portion of the carrier 2. The bottom of the recess 35 is formed asan abutting wall 36. The outside of the bottom of the recess 35 abutsthe doors 23. Both of the two, upper and lower openings 22 are formed inthe abutting wall 36. The two, upper and lower stages 11 are arranged inthe recess 35 for placing the two carriers 2, respectively, so that thetwo carriers 2 abut the abutting wall 36, respectively.

[0044] As shown in FIGS. 3 and 6, each stage 11 has a U-shape in planview, which opens to the side of the operation area S1, in order toprevent interference with the transferring arm 15 of the carriertransferring mechanism 12. Positioning pins 38 protrude from the uppersurface of each stage 11 for fitting in holes (not shown) on the bottomof the carrier 2. Carrier sensors 39 are arranged on the upper surfaceof each stage 11 for detecting whether the carrier 2 is on the stage 11.

[0045] As shown in FIG. 4, carrier fixing air cylinders 40 are arrangedon both sides of the recess 35 as carrier fixing means in order to pressand fix (lock) the front portion of the carrier 2 to a surroundingportion of the opening 22 via the rear surface of the flange 26 of thecarrier 2 (see FIG. 5). The stage 11 is supported movably in afront-rear direction in order to follow the carrier 2 which can be movedby the carrier fixing air cylinders 40. Sealing elements 41 are attachedalong the surrounding portion of each opening 22 in order to providehermetical seal between the carrier 2 and the opening 22 and between themated door 23 and the opening 22 (see FIGS. 7a-7 c).

[0046] As shown in FIG. 4, each door 23 is adapted to be moved into theside of the loading area S2 and in vertical direction by a dooropening-closing mechanism 37, so that the door 23 can be opened. Thedoor 23 facing the carrier 2 on one of the two stages 11 is opened forallowing access to the semiconductor wafers W in the carrier 2. Theother door 23 for the other of the two stages 11 remains closed. In moredetail, as shown in FIGS. 2a and 2 b, the door 23 for the upper stage 11remains closed when the door 23 for the lower stage 11 is opened andretracted upward. To the contrary, the door 23 for the lower stage 11remains closed when the door 23 for the upper stage 11 is opened andretracted downward.

[0047] As shown in FIG. 4, each door 23 has two supporting arms 42extended for facing both outer sides of the recess 35 of the partition6. The door opening-closing mechanism 37, which can operate to open andclose the door 23 as mentioned above, has two vertically movable frames44 supported for vertical movement by two vertical guides 43 on bothouter sides of the recess 35 of the partition 6. Each vertically movableframe 44 is connected with a door-elevating air cylinder 46 which canmove the frame 44 up and down. The supporting arms 42 of the door 23 aresupported movably in a front-rear direction on the vertically movableframes 44 via front-rear guides 45. Door opening-closing air cylinders47 are mounted on the vertically movable frames 44 for moving the door23 in the front-rear direction via the supporting arms 42 to open andclose the door 23. In the embodiment shown in FIG. 4, one (right)door-elevating air cylinder 46 is adapted to move the upper door 23 upand down, and the other (left) door-elevating air cylinder 46 is adaptedto move the lower door 23 up and down.

[0048] A lid opening-closing mechanism 48 is mounted at each door 23 foropening and closing the corresponding lid 25 of the carrier 2independently of the door 23. The lid opening-closing mechanism 48 has afront-rear movable frame 49 arranged movably in a front-rear directionin front of the door 23. The key handling mechanism 27 is incorporatedin the front-rear movable frame 49. In FIG. 4, the front-rear movableframe 49 has two supporting arms 50 extended for facing both supportingarms 42 of the door 23. The supporting arms 50 are supported movably ina front-rear direction on both supporting arms 42 via lidopening-closing air cylinders with guides 51. The partition 6 is alsoformed in such a manner that the thickness of the partition 6 can secureenough space to accommodate the lid 25 in the opening 22 when the lid 25is moved forward from the front of the carrier 2 by the lidopening-closing mechanism 48 and is opened.

[0049] As shown in FIGS. 7a-7 c, bores 52 are formed in each door 23.The rotating shafts 33 of the key handling mechanism 27 incorporated inthe front-rear movable frame 49 of the lid opening-closing mechanism 48pass through the bores 52 slidably in a front-rear direction androtatably with respect to the door 23.

[0050] As shown in FIG. 9, a sealing element 53 such as an O-ring isattached to the inside of each bore 52 as means for sealing between therotating shaft 33 and the bore 52. Exhaust grooves 54 and exhaust bores55 are formed in each door 23 for exhausting any gas around the bores 52and the keys 28 to evacuate the area in cooperation with a vacuum pump(not shown). This ensures prevention of leakage of the air in theoperation area S1 into the loading area S2 through a space between thebores 52 and the rotating shafts 33. This also serves as measuresagainst particles around the keys 28.

[0051]FIG. 8 shows an inert gas replacing means 56 provided in eachopening 22 for replacing a gas in the corresponding carrier 2 with aninert gas by introducing the inert gas into the carrier 2 when thecorresponding door 23 closes the opening 22 and the lid 25 is opened bythe lid opening-closing mechanism 48. As shown in FIGS. 7 and 8, theinert gas replacing means 56 comprises inert gas supplying holes 57 andgas exhausting holes 58 which are formed in inside edges of the opening22. The inert gas may be nitrogen (N₂). As shown in FIG. 8, the inertgas supplying holes 57 are formed preferably in one of right and leftsides of the opening 22 at a desirable interval, and the gas exhaustingholes 58 are formed preferably in the other of right and left sides ofthe opening 22 at the same interval, so that the inert gas can flow in adirection parallel with the surface of the semiconductor wafers W housedin the carrier 2. This ensures that the interior of the carrier 2 andthe interior of the opening 22 can be very smoothly replaced with theinert gas.

[0052] The inert gas supplying holes 57 are connected with an inert gassupplying source via inert gas supplying tubes. The exhausting holes 58are connected with an exhausting system via exhausting tubes 60. Asensor for detecting oxygen density (not shown) is mounted in theexhausting tubes 60. The operation of the inert gas replacement isfinished when the oxygen density sensor detects a density value lessthan a prescribed density value. Then the door 23 is opened andretracted. The lid 25 is opened and retracted together with the door 23when the door 23 is opened and retracted. The operation of opening andclosing of the lid 25, the operation of the inert gas replacement, theoperation of opening and closing of the door 23 and so on are controlledby a control unit (not shown) in accordance with a prescribed program.The numeral sign 61 in the FIGS. 7a to 7 c designates a sealing elementfor sealing between the carrier 2 and the lid 25.

[0053] The operation of the processing unit in the embodiment and theprocessing method using the processing unit will be described hereafter.First, a carrier 2 is transferred and placed on one stage 11 by thecarrier transferring mechanism 12. If the carrier sensors 39 detect thatthe carrier 2 is placed on the stage 11, the carrier fixing aircylinders 40 are driven to press the carrier 2 so that the carrier 2 issealingly fixed to the opening 22 in the partition 6. At that time, theopening 22 is closed by the door 23 and the keys 28 are withdrawn to theopening 22 for preventing the interference with the carrier 2.

[0054] Then, as shown in FIG. 7a, the inert gas replacing means 56remove the air of the space between the door 23 and the lid 25 andsupply the inert gas into the same space, in the state where the door 23is sealingly closed and the lid 25 is closed.

[0055] Then, the lid 25 of the carrier 2 is opened and the inert gasreplacing means 56 replace the interior of the carrier 2 with the inertgas while the door 23 remain closed. In more details, as shown in FIG.7a, the lid opening-closing mechanism 48 operates as follows.

[0056] The keys 28 are moved forward to the lid 25 of the carrier 2 bythe front-rear movable frame 49 until the keys 28 are inserted into thekey holes 29 of the lid 25. The keys 28 are then rotated in thedirection to release the lock of the lid 25. As shown in FIG. 7b, thekeys 28 are moved rearward together with the lid 25 until the lid 25abuts on the door 23 in the opening 22.

[0057] Then, the original gas in the carrier 2 is exhausted via theexhausting holes 58, and the inert gas such as nitrogen (N₂) is suppliedinto the carrier 2 via the inert gas supplying holes 57. In moredetails, the inert gas is supplied from the supplying holes 57 on oneside of the opening 22 into the carrier 2 through the gap between thecarrier 2 and the lid 25, and the gas such as remaining air in thecarrier 2 and the opening 22 is exhausted from the exhausting holes 58on the opposite side of the opening 22. That is, the interior of thecarrier 2 and the interior of the opening 22 are replaced with the inertgas. The timing for starting the supplement of the inert gas may be setfreely between the timing for fixing the carrier 2 to the opening 22 andthe timing for opening the lid 25 of the carrier 2.

[0058] The sensor for detecting oxygen density detects whether theinterior of the carrier 2 is satisfactorily replaced with the inert gas.If the interior of the carrier 2 is satisfactorily replaced with theinert gas, the supplement of the inert gas comes to a stop. Then, asshown in FIG. 7c, the lid 25 is opened and retracted upward togetherwith the door 23 to openly communicate the interior of the carrier 2with the loading area S2. The semiconductor wafers W in the carrier 2are then transferred into the wafer-boat 4 by the transferring mechanism19. After the carrier 2 becomes empty, the door 23 and the lid 25 areclosed. The empty carrier 2 on the stage 11 is replaced with anothercarrier 2 in the storing sections 10. The above operations are repeateduntil a prescribed number of, for example 100 to 150, semiconductorwafers W are transferred into the wafer-boat 4.

[0059] Then, the wafer-boat 4 including the prescribed number of thesemiconductor wafers W is loaded into the thermal processing furnace 5.The semiconductor wafers W undergo the prescribed heat process. Afterthe heat process has finished, the wafer-boat 4 is unloaded from thethermal processing furnace 5. The processed semiconductor wafers W inthe wafer-boat 4 are transferred into the empty carrier 2 in the reverseorder of the above operations.

[0060] As described above, when the carrier 2 abuts on the opening 22 onthe atmospheric side, the door 23 closing the opening 22 and the lid 25are opened not at the same time but only the lid 25 is opened while thedoor 23 remains closed, the interior of the carrier 2 is replaced withthe inert gas, and then the door 23 is opened to openly communicate theinterior of the carrier 2 with the loading area S2. Thus, it can beprevented that the air leaks from the atmospheric operation area S1 orfrom the interior of the carrier 2 into the loading area S2. Therefore,the replacement of the loading area S2 with the inert gas needs lesstime, and the forming of the natural oxidation film on the semiconductorwafers W is prevented so that the process has no adverse effect. Thatis, this unit can perform the process of the semiconductor wafers Wwithout increasing the concentration of the oxygen by the air in thecarrier 2, so that the throughput and the yield are improved.

[0061] This invention is not limited by the above embodiment and may bemodified variously within the scope of claim. For example, as shown inFIG. 10, the carrier fixing means may comprise a carrier lock mechanism64. The carrier lock mechanism 64 has a lock arm 66 supported rotatablyby a shaft 65, adjacent to the opening 22 in the partition 6. The lockarm 66 is adapted to be rotated to press and fix the flange 26 of thecarrier 2. Additionally, as shown in FIG. 11, the lid opening-closingmechanism 48 may comprise a front-rear movable frame 49 withoutsupporting arms 50 for simplification of the structure and space-saving.The front-rear movable frame 49 is movable in a front-rear direction infront of the door 23 via air cylinders 67.

1. A processing unit for a substrate comprising; a partition providedbetween an atmospheric area and an inert gas area, and having an openingto communicate the atmospheric area with the inert gas area, a doorprovided at the opening to open and close it, carrier holding means forholding a carrier for the substrate in such a manner that the carriercomes in contact with the opening on the side of the atmospheric area,and inert gas replacing means for replacing a gas in the carrier with aninert gas by introducing the inert gas into the carrier when the doorcloses the opening and the carrier comes in contact with the opening onthe side of the atmospheric area by the carrier holding means.
 2. Aprocessing unit according to claim 1 , wherein: the carrier has anopening part to communicate with the opening when the carrier comes incontact with the opening on the side of the atmospheric area, and theinert gas replacing means has an inert gas supplying hole and a gasexhausting hole which are openly provided in the opening.
 3. Aprocessing unit according to claim 1 , wherein: the carrier has a lid toopen and close the opening part of the carrier.
 4. A processing unitaccording to claim 3 , further comprising: a lid opening-closingmechanism mounted on the door for holding the lid of the carrier and foropening and closing it.
 5. A processing unit according to claim 4 ,further comprising; a door opening-closing mechanism mounted on thepartition for opening and closing the door, and wherein: the dooropening-closing mechanism is adapted to open the door in a state wherethe lid opening-closing mechanism holds the lid of the carrier.
 6. Aprocessing unit according to claim 1 , wherein: the carrier holdingmeans has carrier positioning means for positioning the carrier in sucha manner that the carrier comes in sealing contact with the opening onthe side of the atmospheric area.
 7. A processing unit according toclaim 1 , wherein: the carrier and the opening in the partition areadapted to come in sealing contact with each other via a sealingelement.
 8. A processing unit according to claim 1 , wherein: thepartition has a second opening to communicate the atmospheric area withthe inert gas area, and further comprising; a second door provided atthe second opening to open and close it, second carrier holding meansfor holding a carrier for the substrate in such a manner that thecarrier comes in contact with the second opening on the side of theatmospheric area, and second inert gas replacing means for replacing agas in the carrier with an inert gas by introducing the inert gas intothe carrier when the second door closes the second opening and thecarrier comes in contact with the second opening on the side of theatmospheric area by the second carrier holding means.
 9. A processingunit according to claim 8 , wherein: the door is adapted to movedownward to open the opening, and the second door is adapted to moveupward to open the second opening.
 10. A processing method for asubstrate by using a processing unit for the substrate comprising: apartition provided between an atmospheric area and an inert gas area,and having an opening to communicate the atmospheric area with the inertgas area, a door provided above the opening to open and close it,carrier holding means for holding a carrier for the substrate in such amanner that the carrier comes in contact with the opening on the side ofthe atmospheric area, and inert gas replacing means for replacing a gasin the carrier with an inert gas by introducing the inert gas into thecarrier when the door closes the opening and the carrier comes incontact with the opening on the side of the atmospheric area by thecarrier holding means, said method comprising; a step for closing theopening by the door, a step for holding the carrier including thesubstrate by the carrier holding means in such a manner that the carriercomes in contact with the opening on the side of the atmospheric area, astep for replacing the gas in the carrier with the inert gas by theinert gas replacing means, and a step for opening the door tocommunicate the interior of the carrier replaced with the inert gas withthe inert gas area via the opening.